feat: Add AI knowledge assistant Node.js demo (#276)

* feat: Add AI knowledge assistant Node.js demo

* docs: Added README for AI assistant knowledge app

* fix: Ignore empty text messages in the AI knowledge assistant demo

* fix: Simplify topic configuration and accessory action message in ai-knowledge-app

node/ai-knowledge-assistant/.gcloudignore

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+# This file specifies files that are *not* uploaded to Google Cloud
+# using gcloud. It follows the same syntax as .gitignore, with the addition of
+# "#!include" directives (which insert the entries of the given .gitignore-style
+# file at that point).
+#
+# For more information, run:
+#   $ gcloud topic gcloudignore
+#
+.gcloudignore
+# If you would like to upload your .git directory, .gitignore file or files
+# from your .gitignore file, remove the corresponding line
+# below:
+.git
+.gitignore
+
+node_modules
+test

node/ai-knowledge-assistant/.gitignore

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+node_modules/
+client_secrets.json

node/ai-knowledge-assistant/README.md

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+# Google Chat AI Knowledge Assistant app
+
+This code sample shows how to make a Google Chat app that answers questions
+based on conversations in Chat spaces with generative AI powered by Vertex AI
+with Gemini. The Chat app uses the Google Workspace Events API plus PubSub to
+recognize and answer questions posted in Chat spaces in real time, even when it
+isn't mentioned.
+
+The Chat app uses all the messages sent in the space as a data source and
+knowledge base: when someone asks a question, the Chat app checks for previously
+shared answers and then shares the best one. If no answer is found, it @mentions
+a space manager to ask for an answer. By using Gemini AI, the Google Chat app
+adapts and grows its knowledge base as it continuously trains on conversations
+in spaces it's added to.
+
+The Chat app is implemented as two Google Cloud Function using a Node.js runtime,
+which respond to
+[interaction events](https://developers.google.com/workspace/chat/interaction-events)
+and
+[subscription events](https://developers.google.com/workspace/events/guides/events-chat)
+from Google Chat.
+
+It uses [Vertex AI](https://cloud.google.com/vertex-ai) with the
+[Gemini](https://cloud.google.com/vertex-ai/generative-ai/docs/multimodal/overview)
+model to answer to user questions based on the knowledge base extracted from the
+conversation history.
+
+## Tutorial
+
+For detailed instructions to deploy and run this sample, follow the
+[dedicated tutorial](https://developers.google.com/workspace/chat/tutorial-ai-knowledge-assistant)
+in the Google Chat developer documentation.
+
+## Scripts
+
+- `npm run test` : Executes all the unit tests.
+- `./deploy.sh`  : Deploys the two Cloud Functions to GCP using gcloud CLI.

node/ai-knowledge-assistant/controllers/app.js

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+/**
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @fileoverview The main application logic. Processes the
+ * [Chat event](https://developers.google.com/workspace/chat/interaction-events).
+ * It handles Chat app mentions and added to space events.
+ */
+
+const { env } = require('../env.js');
+const { AppAuthChatService } = require('../services/app-auth-chat-service');
+const { AppAuthEventsService } = require('../services/app-auth-events-service');
+const { FirestoreService } = require('../services/firestore-service');
+const { UserAuthChatService } = require('../services/user-auth-chat-service');
+const { UserAuthEventsService } = require('../services/user-auth-events-service');
+const { generateAuthUrl } = require('../services/user-auth.js');
+
+/**
+ * Google Chat
+ * [event types](https://developers.google.com/workspace/chat/interaction-events).
+ * @enum {string}
+ */
+const EventType = {
+  MESSAGE: 'MESSAGE',
+  ADDED_TO_SPACE: 'ADDED_TO_SPACE',
+  REMOVED_FROM_SPACE: 'REMOVED_FROM_SPACE',
+  CARD_CLICKED: 'CARD_CLICKED',
+}
+
+/**
+ * Chat application logic.
+ */
+class ChatApp {
+  /**
+   * Instantiates the Chat app.
+   * @param {!Object} event The
+   * [event](https://developers.google.com/workspace/chat/interaction-events)
+   * received from Google Chat.
+   */
+  constructor(event) {
+    this.event = event;
+    this.spaceName = event.space.name;
+    this.userName = event.user.name;
+    this.configCompleteRedirectUrl = event.configCompleteRedirectUrl;
+  }
+
+  /**
+   * Executes the Chat app and returns a
+   * [message](https://developers.google.com/workspace/chat/messages-overview)
+   * as a response.
+   * @return {Promise<import('@googleapis/chat').chat_v1.Schema$Message>} A
+   *     message to post back to the space.
+   */
+  async execute() {
+    switch (this.event.type) {
+      case EventType.ADDED_TO_SPACE:
+      case EventType.MESSAGE:
+        return this.handleAddedToSpaceOrMention();
+      case EventType.REMOVED_FROM_SPACE:
+        return this.handleRemovedFromSpace();
+      case EventType.CARD_CLICKED:
+        return this.handleCardClickEvent();
+      default:
+        return {};
+    }
+  }
+
+  /**
+   * Handles the ADDED_TO_SPACE or MESSAGE event by sending back a welcome message.
+   * It also adds the space to storage, queries all messages currently in the space,
+   * and saves all the messages into storage.
+   * @return {Promise<import('@googleapis/chat').chat_v1.Schema$Message>} A
+   *     welcome text message to post back to the space.
+   */
+  async handleAddedToSpaceOrMention() {
+    if (env.logging) {
+      console.log(JSON.stringify({
+        message: 'Saving message history and subscribing to the space.',
+        spaceName: this.spaceName,
+        userName: this.userName,
+      }));
+    }
+    await FirestoreService.createSpace(this.spaceName);
+
+    try {
+      // List and save the previous messages from the space.
+      const messages = await UserAuthChatService.listUserMessages(
+        this.spaceName, this.userName);
+      await FirestoreService.createOrUpdateMessages(this.spaceName, messages);
+
+      // Create space subscription.
+      await UserAuthEventsService.createSpaceSubscription(
+        this.spaceName, this.userName);
+    } catch (e) {
+      if (e.name === 'InvalidTokenException') {
+        // App doesn't have a refresh token for the user.
+        // Request configuration to obtain OAuth2 tokens.
+        return {
+          actionResponse: {
+            type: 'REQUEST_CONFIG',
+            url: generateAuthUrl(this.userName, this.configCompleteRedirectUrl)
+          }
+        };
+      }
+      // Rethrow unrecognized errors.
+      throw e;
+    }
+
+    // Reply with welcome message.
+    const text = 'Thank you for adding me to this space. I help answer'
+      + ' questions based on past conversation in this space. Go ahead and ask'
+      + ' me a question!';
+    return { text: text };
+  }
+
+  /**
+   * Handles the REMOVED_FROM_SPACE event by deleting the space subscriptions
+   * and deleting the space from storage.
+   */
+  async handleRemovedFromSpace() {
+    if (env.logging) {
+      console.log(JSON.stringify({
+        message: 'Deleting space subscriptions and message history.',
+        spaceName: this.spaceName,
+      }));
+    }
+    await AppAuthEventsService.deleteSpaceSubscriptions(this.spaceName);
+    await FirestoreService.deleteSpace(this.spaceName);
+    return {};
+  }
+
+  /**
+   * Handles the CARD_CLICKED event by sending a message to the space manager.
+   * @return {Promise<import('@googleapis/chat').chat_v1.Schema$Message>} A text
+   *     message to post back to the space.
+   */
+  async handleCardClickEvent() {
+    if (env.logging) {
+      console.log(JSON.stringify({
+        message: 'Handling card clicked event.',
+        spaceName: this.spaceName,
+      }));
+    }
+    let text = 'Please answer the question above.';
+    const spaceManagerName =
+      await AppAuthChatService.listSpaceManager(this.spaceName);
+    if (spaceManagerName) {
+      text = `<${spaceManagerName}> ${text}`;
+    }
+    return { text: text };
+  }
+}
+
+module.exports = {
+  /**
+   * Executes the Chat app and returns a
+   * [message](https://developers.google.com/workspace/chat/messages-overview)
+   * as a response.
+   * @param {!Object} event The
+   * [event](https://developers.google.com/workspace/chat/interaction-events)
+   * received from Google Chat.
+   * @return {Promise<import('@googleapis/chat').chat_v1.Schema$Message>} A
+   *     message to post back to the space.
+   */
+  execute: async function (event) {
+    return new ChatApp(event).execute();
+  }
+};